AF_PACKET support for netstack (aka epsocket).

Like (AF_INET, SOCK_RAW) sockets, AF_PACKET sockets require CAP_NET_RAW. With
runsc, you'll need to pass `--net-raw=true` to enable them.

Binding isn't supported yet.

PiperOrigin-RevId: 275909366

2 files changed, 25 insertions, 8 deletions

diff --git a/pkg/tcpip/link/sharedmem/sharedmem.go b/pkg/tcpip/link/sharedmem/sharedmem.go
index 9e71d4edf..4393403c5 100644
--- a/pkg/tcpip/link/sharedmem/sharedmem.go
+++ b/pkg/tcpip/link/sharedmem/sharedmem.go
@@ -212,6 +212,21 @@ func (e *endpoint) WritePacket(r *stack.Route, _ *stack.GSO, hdr buffer.Prependa
 	return nil
 }
 
+// WriteRawPacket implements stack.LinkEndpoint.WriteRawPacket.
+func (e *endpoint) WriteRawPacket(packet buffer.VectorisedView) *tcpip.Error {
+	v := packet.ToView()
+	// Transmit the packet.
+	e.mu.Lock()
+	ok := e.tx.transmit(v, buffer.View{})
+	e.mu.Unlock()
+
+	if !ok {
+		return tcpip.ErrWouldBlock
+	}
+
+	return nil
+}
+
 // dispatchLoop reads packets from the rx queue in a loop and dispatches them
 // to the network stack.
 func (e *endpoint) dispatchLoop(d stack.NetworkDispatcher) {
@@ -254,7 +269,7 @@ func (e *endpoint) dispatchLoop(d stack.NetworkDispatcher) {
 
 		// Send packet up the stack.
 		eth := header.Ethernet(b)
-		d.DeliverNetworkPacket(e, eth.SourceAddress(), eth.DestinationAddress(), eth.Type(), buffer.View(b[header.EthernetMinimumSize:]).ToVectorisedView())
+		d.DeliverNetworkPacket(e, eth.SourceAddress(), eth.DestinationAddress(), eth.Type(), buffer.View(b[header.EthernetMinimumSize:]).ToVectorisedView(), buffer.View(eth))
 	}
 
 	// Clean state.
diff --git a/pkg/tcpip/link/sharedmem/sharedmem_test.go b/pkg/tcpip/link/sharedmem/sharedmem_test.go
index 0e9ba0846..f3e9705c9 100644
--- a/pkg/tcpip/link/sharedmem/sharedmem_test.go
+++ b/pkg/tcpip/link/sharedmem/sharedmem_test.go
@@ -78,9 +78,10 @@ func (q *queueBuffers) cleanup() {
 }
 
 type packetInfo struct {
-	addr  tcpip.LinkAddress
-	proto tcpip.NetworkProtocolNumber
-	vv    buffer.VectorisedView
+	addr       tcpip.LinkAddress
+	proto      tcpip.NetworkProtocolNumber
+	vv         buffer.VectorisedView
+	linkHeader buffer.View
 }
 
 type testContext struct {
@@ -130,12 +131,13 @@ func newTestContext(t *testing.T, mtu, bufferSize uint32, addr tcpip.LinkAddress
 	return c
 }
 
-func (c *testContext) DeliverNetworkPacket(_ stack.LinkEndpoint, remoteLinkAddr, localLinkAddr tcpip.LinkAddress, proto tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
+func (c *testContext) DeliverNetworkPacket(_ stack.LinkEndpoint, remoteLinkAddr, localLinkAddr tcpip.LinkAddress, proto tcpip.NetworkProtocolNumber, vv buffer.VectorisedView, linkHeader buffer.View) {
 	c.mu.Lock()
 	c.packets = append(c.packets, packetInfo{
-		addr:  remoteLinkAddr,
-		proto: proto,
-		vv:    vv.Clone(nil),
+		addr:       remoteLinkAddr,
+		proto:      proto,
+		vv:         vv.Clone(nil),
+		linkHeader: linkHeader,
 	})
 	c.mu.Unlock()